Computerized ST depression analysis improves prediction of all-cause and cardiovascular mortality: the strong heart study

Association of low-moderate urine arsenic and QT interval: Cross-sectional and longitudinal evidence from the Strong Heart Study

Epidemiologic studies suggest that chronic exposure to arsenic is related to cardiovascular disease (CVD), but the pathophysiological link remains uncertain. We evaluated the association of chronic low-moderate arsenic exposure and arsenic metabolism with baseline difference and annual change in ECG measures (QT interval, JT interval, PR interval, QRS duration, and QT dispersion) using linear mixed models in the Strong Heart Study main cohort (N = 1174, median age 55 years) and family study (N = 1695 diabetes-free, median age 36 years). At baseline, arsenic exposure was measured as the sum of inorganic and methylated species in urine (ΣAs) and arsenic metabolism was measured as the relative percentage of arsenic species. Median ΣAs and Bazett heart rate-corrected QT interval (QTc) were 8.6 μg/g creatinine and 424 ms in the main cohort and 4.3 μg/g and 414 ms in the family study, respectively. In the main cohort, a comparison of the highest to lowest ΣAs quartile (>14.4 vs. <5.2 μg/g creatinine) was associated with a 5.3 (95% CI: 1.2, 9.5) ms higher mean baseline QTc interval but no difference in annual change in QTc interval. In the family study, a comparison of the highest to lowest quartile (>7.1 vs. <2.9 μg/g creatinine) was associated with a 3.2 (95% CI: 0.6, 5.7) ms higher baseline QTc interval and a 0.6 (95% CI: 0.04, 1.2) ms larger annual increase in QTc interval. Associations with JTc interval were similar but stronger in magnitude compared to QTc interval. Arsenic exposure was largely not associated with PR interval, QRS duration or QT dispersion. Similar to arsenic exposure, a pattern of lower %MMA and higher %DMA was associated with longer baseline QTc interval in both cohorts and with a larger annual change in QTc interval in the family study. Chronic low-moderate arsenic exposure and arsenic metabolism were associated with prolonged ventricular repolarization.

Electrocardiographic changes improve risk prediction in asymptomatic persons age 65 years or above without cardiovascular disease

BACKGROUND

Risk prediction in elderly patients is increasingly relevant due to longer life expectancy.

OBJECTIVES

This study sought to examine whether electrocardiographic (ECG) changes provide prognostic information incremental to current risk models and to the conventional risk factors.

METHODS

In all, 6,991 participants from the Copenhagen Heart Study attending an examination at age ≥65 years were included. ECG changes were defined as Q waves, ST-segment depression, T-wave changes, ventricular conduction defects, and left ventricular hypertrophy based on the Minnesota code. The primary endpoint was fatal cardiovascular disease (CVD) event and the secondary was fatal or nonfatal CVD event. In our study, 2,236 fatal CVD and 3,849 fatal or nonfatal CVD events occurred during a median of 11.9 and 9.8 years of follow-up.

RESULTS

ECG changes were frequently present (30.6%) and associated with conventional risk factors. All ECG changes except 1 univariably predicted both endpoints. Event rates of ECG changes versus no ECG changes were respectively 41.4% versus 27.8% and 64.6% versus 50.8%. When added to existing risk scores, ECG changes independently increased the risk of both endpoints. Fatal CVD events: hazard ratio (HR): 1.33 (95% confidence interval [CI]: 1.29 to 1.36; p < 0.001) and fatal or nonfatal CVD events: HR: 1.21 (95% CI: 1.19 to 1.24; p < 0.001). When added to conventional risk factors, continuous net reclassification improvement was 42.3% (95% CI: 42.0 to 42.4; p < 0.001) for fatal and 29.2% (95% CI: 28.4 to 29.2; p < 0.001) for fatal or nonfatal events. Categorical net reclassification was 7.1% (95% CI: 6.7 to 9.0; p < 0.001) for fatal and 4.2% (95% CI: 3.5 to 5.6; p < 0.001) for fatal or nonfatal events.

CONCLUSIONS

Simple assessment of the existence of ECG changes improves risk prediction in the general population of persons age ≥65 years.

Electrocardiographic precordial ST-segment deviations and the risk of cardiovascular death: results from the Copenhagen ECG Study

Background

We sought to perform a study assessing the association between electrocardiographic ST‐segment deviations and cardiovascular death (CVD), in relation to sex and age (≥ and <65 years), in a large primary care population without overt ischemic heart disease.

Methods and Results

Using computerized analysis of ECGs from 285 194 persons, we evaluated the association between precordial ST‐segment deviations and the risk of CVD. All data on medication, comorbidity, and outcomes were retrieved from Danish registries. After a median follow‐up period of 5.8 years, there were 6679 cardiovascular deaths. Increasing ST‐depression was associated with an increased risk of CVD in almost all of the precordial leads, with the most robust association seen in lead V5 to V6. ST‐elevations in lead V2 to V6 were associated with increased risk of CVD in young women, but not in men. However, ST‐elevations in V1 increased the risk for both genders and age groups, exemplified by a HR of 1.80 (95% CI [1.19 to 2.74], P=0.005) for men <65 years with ST‐elevations ≥150 μV versus a nondeviating ST‐segment (−50 μV to +50 μV). In contrast, for men <65 years, ST‐elevations in lead V2 to V3 conferred a decreased risk of CVD with a HR of 0.77 (95% CI [0.62 to 0.96], P<0.001) for ST‐elevations ≥150 μV in V2.

Conclusion

We found that ST‐depressions were associated with a dose‐responsive increased risk of CVD in nearly all the precordial leads. ST‐elevations conferred an increased risk of CVD in women and with regard to lead V1 also in men. However, ST‐elevations in V2 to V3 were associated with a decreased risk of CVD in young men.

T-wave alternans and ST depression assessment identifies low risk individuals with ischemic cardiomyopathy in the absence of left ventricular hypertrophy

BACKGROUND

Although ECG left ventricular hypertrophy (LVH) by Cornell product (CP) predicts increased mortality in patients with ischemic cardiomyopathy (ICM), those without CP LVH remain at relatively high risk. We examined whether T-wave alternans (TWA) testing and ST depression can improve risk stratification in these patients.

METHODS AND RESULTS

This study examined 317 patients with ICM, nonsustained ventricular tachycardia, and a resting ECG in sinus rhythm, who presented for electrophysiology and TWA testing, and potential implantable cardioverter defibrillator (ICD) implantation. LVH was defined by CP :[(RaVL + SV3 ) +6 mm in women] × QRS duration > 2440 mm * msec. ST depression was examined as a categorical variable using an established threshold of depression of ≥50 μV in V5 or V6 . In Cox multivariate models, abnormal TWA testing and ST depression were independent predictors of mortality in patients without CP LVH (HR 2.52, CI 1.09-5.80, P = 0.030 and HR 2.87, CI 1.41-5.81, P = 0.004, respectively). Individuals with no LVH by CP, normal TWA, and no significant ST depression, comprised 23% of the study population and had a 5.6% 3-year mortality, compared to an overall 20% mortality.

CONCLUSIONS

TWA and ST depression testing are strong predictors of mortality among ICM patients without CP LVH, with normal testing conversely predicting low 3-year mortality. Thus, risk assessment with TWA testing and a resting ECG can identify ICM patients at low risk who may be less likely to benefit from ICD implantation.

Quantitative electrocardiographic measures and long-term mortality in exercise test patients with clinically normal resting electrocardiograms

BACKGROUND

Currently, the only function of the resting electrocardiogram (ECG) in patients referred for exercise testing is to determine whether imaging is mandated. It is unknown if subtle ECG findings in those patients with clinically normal resting ECGs have prognostic significance.

METHODS

We performed a single-center cohort study of 18,964 patients without known cardiovascular disease who had a clinically normal resting ECG and who underwent treadmill exercise testing for evaluation of suspected coronary artery disease. Eleven quantitative ECG measures relating to heart rate, conduction, left ventricular mass, or repolarization were collected digitally. The primary outcome was all-cause mortality. The prognostic importance of a composite ECG score was assessed by measuring its impact on the c-index (analogous to area under receiver operating characteristic curve) and by measures of reclassification.

RESULTS

During a median follow-up of 10.7 years, 1,585 patients died. The 4 most predictive digital ECG variables were higher ventricular rate, more leftward QRS axis, more downward ST-segment deviation, and longer QT interval. The ECG score was independently associated with mortality (75th vs 25th percentile hazard ratio 1.36, 95% confidence interval 1.25-1.49, P < .0001). The ECG score had modest impact on discrimination (change in c-index 0.04) and reclassification of risk (3.0% decrease of relative integrated discrimination improvement, P < .001).

CONCLUSIONS

Subtle ECG findings relating to heart rate, conduction, left ventricular mass, or repolarization in patients with clinically normal ECGs referred for exercise testing may provide modest additional prognostic information over and above clinical and exercise measures.

Association between electrocardiographic left ventricular hypertrophy with strain pattern and left ventricular structure and function

BACKGROUND AND PURPOSE

Electrocardiographic left ventricular hypertrophy (LVH) with strain pattern has been documented as a marker for LVH. Its presence on the ECG of hypertensive patients is associated with poor prognosis. The study was carried out to assess the association of the electrocardiographic strain with left ventricular mass (LVM) and function in hypertensive Nigerians.

MATERIAL AND METHODS

ECG as well as echocardiograms were performed in 64 hypertensive patients with ECG-LVH and strain pattern, 65 patients with ECG-LVH by Sokolow-Lyon (SL) voltage criteria and 62 normal controls.

RESULTS

The study showed that electrocardiographic left ventricular (LV) strain pattern is associated with dilated left atrium, larger LV internal dimensions and greater absolute and indexed LVM in hypertensive Nigerians compared with ECG-LVH by SL voltage criteria alone or normal controls.

CONCLUSION

The findings of this study support the fact that the ECG strain pattern is associated with increased LVM and an increased risk of developing abnormal LV geometry.

Sonographic fatty liver, overweight and ischemic heart disease

AIM: To demonstrate the prevalence of sonographic fatty liver, overweight and ischemic heart disease (IHD) among the male workers in Taiwan, and to investigate the possible association of these three factors.

METHODS: From July to September 2003, a total of 2 088 male aircraft-maintenance workers aged from 22 to 65 years (mean 40.5) underwent an annual health examination, including anthropometrical evaluation, blood pressure measurement, personal medical history assessment, biochemical blood analysis, abdominal ultrasonographic examination and digital electrocardiography (ECG). The Student’s t-test, χ2 test and multivariate logistic regression analysis were utilized to evaluate the relationship between IHD and salient risk factors.

RESULTS: The all-over prevalence of overweight was 41.4%, and that of fatty liver was 29.5% (mild, moderate and severe fatty liver being 14.5%, 11.3%, and 3.7%, respectively); while the prevalence of ischemic changes on ECG was 17.1% in this study. The abnormal rates for conventional IHD risk factors including hypertension, dyslipidemia, hyperglycemia and overweight increased in accordance with the severity of fatty liver. Overweight and severity of fatty liver were independently associated with increased risks for developing IHD. Overweight subjects had a 1.32-fold (95%CI: 1.01-1.73) increased IHD risk. Participants with mild, moderate, and severe fatty liver had a 1.88-fold (95%CI: 1.37-2.6), 2.37-fold (95%CI: 1.66-3.37) and 2.76-fold (95%CI: 1.62-4.72) increased risk for developing IHD. The prevalence of ischemic ECG for the fatty liver-affected subjects with or without overweight was 30.1% and 19.1%, while that of overweight subjects free from fatty liver was 14.4%. Compared to the subjects without fatty liver nor overweight, IHD risk for the three subgroups above was as follows: OR: 2.95 (95%CI: 2.31-4.09), OR: 1.60 (95%CI: 1.07-2.39) and OR: 1.11 (95%CI: 0.78-1.56), respectively.

CONCLUSION: The presence of fatty liver and its severity should be carefully considered as independent risk factors for IHD. Results of the study suggest the synergistic effect between fatty liver and overweight for developing IHD. Abdominal sonographic examination may provide valuable information for IHD risk assessment in addition to limited report about liver status, especially for overweight males.

C-Reactive Protein and Electrocardiographic ST-Segment Depression Additively Predict Mortality

OBJECTIVES

This study was designed to examine whether high-sensitivity C-reactive protein (CRP) and electrocardiographic (ECG) ST-segment depression (STD) have additive utility for predicting cardiovascular disease (CVD) death and all-cause death (ACD).

BACKGROUND

C-reactive protein, a marker of systemic inflammation, and ECG STD, an index of myocardial ischemia and hypertrophy, independently predict mortality.

METHODS

Electrocardiograms and CRP levels were examined in 2,155 American Indian participants in the second Strong Heart Study examination. ST-segment depression >/=50 microV (n = 127) and CRP >7.0 mg/l (defining the upper quartile of CRP levels, n = 540) were considered abnormal.

RESULTS

After 5.2 +/- 1.2 years follow-up there were 95 CVD deaths and 310 ACD. In univariate Cox analyses, the combination of CRP and ECG STD improved risk stratification compared to either alone, with the presence of both CRP >7.0 and ECG STD associated with a 7.7-fold increased risk of CVD death (95% confidence interval [CI] 3.3 to 18.2) and a 6.5-fold increased risk of ACD (95% CI 4.1 to 10.3). After adjustment for age, gender, and relevant risk factors, the combination of high CRP and STD remained predictive of CVD death and ACD, with the presence of both abnormal CRP and STD associated with the highest risks of CVD death (hazard ratio [HR] 3.2, 95% CI 1.1 to 10.5) and ACD (HR 3.9, 95% CI 2.1 to 7.2) and the presence of either high CRP or abnormal STD associated with intermediate risks of CVD death (HR 2.2, 95% CI 1.4 to 3.4) and ACD (HR 1.5, 95% CI 1.2 to 2.0).

CONCLUSIONS

The combination of ECG STD and CRP increases the risk of mortality, demonstrating the additive impacts of active inflammation and preclinical CVD on prognosis.

Combined Echocardiographic Left Ventricular Hypertrophy and Electrocardiographic ST Depression Improve Prediction of Mortality in American Indians

Echocardiographic left ventricular hypertrophy (Echo-LVH) and ST segment depression (STD) on the ECG have each been demonstrated to predict cardiovascular (CV) and all-cause (AC) mortality. However, the prognostic value of combining Echo-LVH and ECG-STD has not been examined. ECGs and echocardiograms were examined in 2193 American Indian participants in the second Strong Heart Study examination. STD was measured by computer and was considered abnormal if > or =50 microV. Echo-LVH was defined by indexed LV mass >116 g/m2 in men and >104 g/m2 in women. After a mean follow-up of 3.1+/-0.7 years, there were 57 CV and 169 AC deaths. In univariate Cox analyses, Echo-LVH (chi2=54.2 and chi2=68.5) and ECG-STD (chi2=35.9 and chi2=46.3, all P<0.001) predicted CV and AC mortality, respectively. The combination of Echo-LVH and ECG-STD improved risk stratification compared with either alone for both CV death (chi2=74.4, P<0.001) and AC death (chi2=102.0, P<0.001), with presence of both ECG-STD and Echo-LVH associated with the greatest risks. After adjustment for age, sex, and relevant risk factors, combined Echo-LVH and ECG-STD remained predictive of CV mortality (chi2=19.7, P<0.001) and AC mortality (chi2=24.9, P<0.001), with the presence of both Echo-LVH and ECG-STD associated with a 6.3-fold increased risk of CV death (95% CI: 2.8 to 14.2) and a 4.6-fold increased risk of AC mortality (95% CI: 2.5 to 8.5). ECG-STD and Echo-LVH additively increase the risk of both CV mortality and AC mortality. These findings support the value of combining Echo-LVH and ECG-STD to improve risk stratification. These findings require verification in other populations.

Electrocardiographic repolarization complexity and abnormality predict all-cause and cardiovascular mortality in diabetes: the strong heart study

Type 2 diabetes is associated with increased risk of cardiovascular (CV) and all-cause mortality. Although electrocardiographic measures of repolarization abnormality and complexity stratify risk in the general population, their prognostic value in diabetes has not been well characterized. Digital electrocardiogram (ECG) readings were acquired for 994 American Indians with type 2 diabetes. ST segment depression (STD) >/=50 micro V and rate-corrected QT interval (QTc) >460 ms were examined as measures of repolarization abnormality. The principal component analysis (PCA) of the ratio of the second to first eigenvalues of the T-wave vector (PCA ratio) (>32.0% in women and >24.6% in men) was examined as a measure of repolarization complexity on the ECG. After a mean follow-up of 4.7 +/- 1.0 years, there were 56 CV deaths and 155 deaths from all causes. In univariate analyses, STD, QTc, and the PCA ratio predicted CV and all-cause mortality. After multivariate adjustment for age, sex, and other risk factors, STD (hazard ratio 3.68, 95% CI 1.70-7.96) and PCA ratio (2.61, 1.33-5.13) remained predictive of CV mortality and both STD (2.36, 1.38-4.02) and QTc (2.03, 1.32-3.12) predicted all-cause mortality. Computerized ECG measures of repolarization abnormality and complexity predict CV and all-cause mortality in type 2 diabetes, supporting their use to identify high-risk individuals with diabetes.

Quantitative assessment of electrocardiographic strain predicts increased left ventricular mass: the Strong Heart Study

OBJECTIVES

This study was designed to examine the relation of computer-measured ST depression (STdep) in the lateral precordial leads to the presence of left ventricular hypertrophy (LVH).

BACKGROUND

Qualitative abnormalities of repolarization in the lateral precordial leads of the electrocardiogram, as manifested by the strain pattern of T-wave inversion and STdep, are markers for LVH and adverse prognosis. However, the independent relationship of increased left ventricular (LV) mass to quantitative measures of STdep in these leads remains unclear.

METHODS

Electrocardiograms and echocardiograms were examined in the second Strong Heart Study examination in 1,595 American Indian participants without evident coronary disease. The absolute magnitude of ST segment deviation above or below isoelectric baseline was measured by computer in leads V(5) and V(6), and participants were grouped according to gender-specific quartiles of maximal STdep. Left ventricular hypertrophy was defined by indexed LV mass >49.2 g/m(2.7) in men and >46.7 g/m(2.7) in women.

RESULTS

Increasing STdep was associated with older age, greater pulse pressure, serum fibrinogen levels and urinary albumin/creatinine ratios, and with stepwise increases in LV mass (145 +/- 28 vs. 150 +/- 33 vs. 156 +/- 36 vs. 164 +/- 43 g, p < 0.001), indexed LV mass (38.2 +/- 7.7 vs. 39.3 +/- 8.7 vs. 40.5 +/- 9.4 vs. 44.0 +/- 11.0 g/m(2.7), p < 0.001), and prevalence of LVH (11.6 vs. 19.1 vs. 21.5 vs. 31.2%, p < 0.001). After controlling for clinical differences, increasing STdep remained strongly associated with increased prevalence of LVH (p = 0.0001).

CONCLUSIONS

In the absence of evidence of coronary disease, increasing STdep in the lateral precordial leads is associated with increasing LV mass and increased prevalence of anatomic LVH.